Acceleration responsive device



Feb. 10, 1942. c. L. EKSERGIAN ET AL 2,272,501

CCELERATION RESPONSIVE DEVICE Filed Jan. 1l, 1939 2 Shee'ts-Sheet 1 5729 L15 INVENTORS Vai/alas Elise @gwn mf H., 000m es a W ATTORNEY Feb.10, 1942. c. L. EKSERGIAN ET AL ACCELERATION RESPONSIVE DEVICE FiledJan. l1, 1939 2 Sheets-Sheet 2 INVENTOR@ @um d HC 'UUmZeS an RNE;

0 j w M A .Z m, @J Y B Patented Feb. 10,' 1942 ACCELERATION RESPONSIVEDEVICE and Joseph H. Coombes, Detroit, Mich., assignors to Budd WheelCompany, Philadelphia, Pa., a corporation of Penn- Carolus L.

sylvanla Application January 11, 1939, Serial No. 250,276

9 Claims.

The present invention relates to means which will respond to angularacceleration of a rotating.

member, in either sense, that is, when the velocity either increases ordecreases. These two changes of velocity are often popularly calledacceleration and deceleration, respectively, but for the purposes of thepresent discussion the term acceleration is to be understood in itscorrect physical meaning, to include change of velocity in eitherdirection and, therefore, to embrace both said concepts.

The device comprises an inertia element which is carried by a rotatingmember and which normally rotates with said member and at the sameangular velocity, but which temporarily deviates in angular velocityfrom said member whenever any substantial acceleration in the motion isinitiated.

The deviation in the rates of the inertia element and the rotatingmember is utilized in accordance with the present invention to produce asignal or a control impulse.

In one type of the invention, it comprises two coaxially mountedrotating elements, one of which has a certain amount of free play withrespect to the other, and which are so mounted that when there is anacceleration in the motion one of the members will shift with respect tothe other and thereby produce a mechanical or electrical effect.

More specifically, the invention contemplates mounting an inertia ringupon the axle or hub of a wheel, said inertia ring being free to move toa limited extent with respect to the wheel and in so moving being causedto shift toward or away from the wheel, thereby providing the electricalcontact or mechanical impulse above mentioned.

Still more specifically, the present invention relates to means intendedprimarily to cooperate with vehicle wheels and axles to produce anelectrical impulse whenever the vehicle is accelerated, regardless ofthe direction of rotation or the angular velocity of said rotatingelements, whereby any desired physical eifect may be initiated such, forexample, as the control of a brake or the actuation of an indicator orrecorder, etc.

Several embodiments of the invention are disclosed in the presentspecification and the accompanying drawings, wherein:

Fig. 1 is an elevation of a vehicle wheel having mechanism illustratedin Fig. l on the plane indicated by the line 2-2, looking in thedirection of the arrows,

Fig. 3 is a fragmentary elevation showing part of the inertia ring, andthe electrical contacts cooperating therewith,

Fig. 4 is a fragmentary cross-section through portion of the mechanismshown in Fig. 1 on the plane indicated by the line 4-4, looking in thedirection of the arrows,

Fig. 5 is an end view of a modied form,

Fig. 6 is a fragmentary axial section through the device shown in Fig.5, the section being made on the plane indicated by the line 6 4,looking in the direction of the arrows and the axle housing being shownin elevation,

Fig. 'I is a plan view partly broken away, and partly in section, toshow one of the rollers and cooperating parts,

Fig. 8 is an end view, partly broken away and partly in section of astill further modification,

Fig. 9 is a longitudinal section through the structure shown in Fig. 8,the section being made on the plane indicated by the line 9 9, lookingin the direction of the arrows, and

Fig. l0 is a circuit diagram illustrating certain electrical deviceswhich may be used in connection with the invention.

Referring first to Fig. 1, the wheel I there shown is loosely mountedwith respect to the housing I4 which surrounds the axle 2. The hub 3 ofthe wheel has an annular member. or flange 4 secured thereto in anysuitable way, for example by means of the cap screws 5, so that themember 4 will rotate with the wheel I.

The member 4 rotates freely about the collar 6 which may have a numberof shoulders turned or otherwise formed therein, as shown at 'I, tocooperate with similar shoulders 8 in the element 4, the collar 6 beingsecured to the housing I4 in any desired way.

A further annular member or collar 9 is secured to the member 4 in anysuitable manner. for example by means of the cap screws I l, so that thecollar 9 will rotate with the wheel I. This collar 9 has a tubularportion II projecting along the housing I4 and rotatable around saidhousing. The tubular portion II has an outer cylindrical face I2 whichin the present instance has three spaced grooves therein, one suchgroove being shown at I3. This groove I3 is shown in plan view in Fig. 3and may be described in general as having a curved bottom and extendingin both directions from'a central point, as shown in Fig. 3. While threesuch grooves are provided as a convenient'l number, it

'rotates with the wheel I.

is, of course, clear that more or less may be found y satisfactory andthere is no reason why any other arbitrary number of such grooves couldnot be provided if desired.

A roller Il cooperates with each groove il and has its peripheralsurface Ii suitably curved to nt and cooperate with such grooves. Eachroller Il is mounted on a suitable pivot, for example. the shank of abolt I1 which passes through the roller, so that said roller may rotatefreely thereon.

Two properly spaced rings il and IB form the anchorages for the boltsI1, which may have their heads 2l countersunk in one of the rings, forexample the ring I5, and project through the other ring Il to whichthey'may then be secured in any desired way, for instance by means ofthe nuts 2i. Suitable lock washers 22 or any other satisfactory meansmay be provided to keep the nuts 2| from loosening on the respectivebolts in service.

Ihe rings il and Il are maintained at the correct spacing from oneanother by rigid elements such as the cross bars or pins 2l, 24, anydesired number of which may be provided. These cross bars or pins are ofproper length to cause the rollers I5 to fit snugly between the ringswhen the nuts 2l are tightened on the bolts I1, so that while therollers Il are capable of turning easily and smoothly on the said bolts.nevertheless there is practically no end play between them and therespective rings.

Attached to any available portion of the collar I is a lug 2l, Figs. 3and 4, which, therefore, This lug 25 serves as the attachment point fora pair of helical springs 2l and 21 which are suitably connected to thelug 25 by means of pins or hooks 28. The remaining end of the spring 2lis secured to any suitable portion of either ring 4Il or Il or anymember which moves therewith, for example the spacing member 23. andsimilarly the remaining end of spring 21 is held by the spacing member24. The springs 2l and 21, therefore, serve as a resilient connectionbetween the collar l and the pair of rings Il and i9. A suitableprotective housing 25' mounted on an end flange ll may be secured to thehousing I4 so as to protect the rings Il, I! and the parts cooperatingtherewith against the entrance of dirt, oil, or

water in service.

Also secured to the hub 3 of the wheel is a suitable brake member Ilwhich is held to said hub in any feasible manner, for instance by meansof a ange 32 which may be fastened to the wheel hub I by the same capscrews 5 which hold the annular member 4 to the said hub. This brakemember Il in the form shown has two annular friction surfaces 33 and 34formed on the outside faces of the two rings 35 and 36, which are spacedapart by the cooling vanes 31. This type of brake ring is disclosed andclaimed in co-pending application Serial No. 159,844, flied August 19,1937, now Patent No. 2,214,762, to which reference should be had for anyneces sary details. It suffices for the present instance to mention thatsuitable brake shoes will cooperate with the friction surfaces 3l and34to provide the desired braking action, when pressed laterally againstsaid friction surfaces.

The flange 30, in addition to forming a pro tectlve closure for one endof the casing 25, also serves as a stationary anchorage for suitableelectrical contact mechanism, as shown best in Figs. 1 and 3.

A bolt 38, which may be mounted in a lug Il projecting inwardly from aportion of the flange Il, may be insulated from said flange by aninsulating sleeve 4l and insulating washers Il, 4i. `A resilient member42 such as a leaf spring, may be secured under the head 43 of said boltand a nut I4 may be threaded on the other end of the bolt J8 so as tosecure the attachment lug or connector 45 firmly to the said flange,while maintaining it electrically insulated therefrom. The insulatedconductor 4B, which is electrically connected to the connector 4l isthus put into permanent electrical connection with the spring 42.

At its other end the spring 42 carries on one side a head 41 preferablymade of insulating material and on its other surface a contact member 4lin electrical connection with the spring 42. A cooperating contactmember 4! is suitably mounted in the lug I9, insulating bushings 5D and5| being applied thereto the maintain the contact 49 electricallyinsulated from the flange 30. The contact 43 is preferably in the formof a pin which may slide longitudinally within the bushings 50 and 5I,and preferably has a collar 52 thereon which is engaged by a spring 5lor the like which urges the pin 49 away from the bushing 5I, that is,toward the cooperating contact 48. The spring 53, however, permitscontact 4s to yield when contact I8 engages it, so as to avoid anyjamming action or undue pressure in operation of the device. Theinsulating bushings 50 and 5| are mounted so as to bear againstshoulders in the lug 39 as shown, to prevent their dislodgernent andmaintain th'em in the proper portion.

The slidable pin or contact 4! is suitably connected to the conductor54, which is electrically connected to the connector lug 55, held by thenut 56, and permanently in electrical connection with the pin or plunger48. This may be accomplished in am of the ways well known in theelectrical art.

A stop member 51 may also be provided to limit the travel of theresilient member 42 and this stop member 51, if not itself made ofinsulation must of course be suitably insulated from the flange 3B so asnot to provide any electrical connection between th'e member 42 and theflange IU. A suitable device for this purpose consists of the bushing58, which may be threaded into the lug 39 as shown, and which providesfor adjusting the member 51 longitudinally in any desired way, forexample, by means of the nut 59. The sole purpose of the stop member 51is to prevent the free end 41 of the spring 42 from projecting too faraway from the adjacent surface of the lug 39, in order normally to keepthe said portion 41 out of contact with the ring i9 and thus prevent itfrom wearing out.

The casing 28 preferably is made in halves, for example as shown in Fig.2, and these halves are secured to one another in any desired way, as bymeans of the bolts 5i) and nuts 6i.

Referring now to the modified form illustrated in Figs. 5, 6 and 7, idesignates the wheel having a hub 3, said hub having a tubular extension64 with a cylindrical outer surface 5I having formed therein a suitablenumber of grooves 66, three grooves being shown in the present example.Each of these grooves Il is inclined at a slight angle to the generalperipheral direction of the cylindrical surface 55, as shown clearly inFig. 7, and each of the grooves is of proper width to receive snugly butyet freely the periphery of one of a corresponding number of rollers 61,three of these being shown, as will be best seen from Fig. 5

Each roller A61 is carried upon a shaft or pin 68, which in turn ismounted in bearings or bushings 69 suitably disposed in lugs 10projecting from the inner surfaces of the two rings 62 and 63 which aremounted a suitable fixed distance apart as, for example, by means ofspacing members or pins 13, 14, and 16, the whole being so arranged thatthe rollers 61 may rotate freely about their own axes but yet withoutany lost motion or play.

A suitable lug 16 may be secured to the tubular member 64 and carry apivot 11 serving as an anchorage for the springs 18 and 19, which extendfrom said pivot 11 respectively in opposite directions, their remainingends being secured to the pins 13 and 14 which are rigidly connected tothe two rings. The pair of rings 62 and 63 will thus be held to therotating hub solely by means of the three rollers 61 andthe two springs18 and 19, said springs being so arranged that normally the rollers 61will maintain said two rings 62 and 63 in a central position withrespect to the portion 65 of the tubular extension 64.

For protection against water, dirt and the like, it is preferred toenclose the rings 62 and 63 within a casing which may conveniently bemade of two sections 1| and 12 held together by means of bolts 80 andnuts 8|. This casing may be secured to any stationary part of thevehicle and serves also as a convenient support for electrical contactswhich cooperate with the rings 62 and 63. These contacts are housed inthe containers 82 and 83, each of which preferably holds two contactswhich are insulated from the containers and from each other. Each ofthese contacts preferably is resilient or yieldably mounted, although itis not absolutely necessary.

The container 82 supports the contacts 84 and 85, and similarly thecontainer 83 supports the contacts 86 and 81, these contacts havingtheir inner ends disposed in proper positions to coopcrate with therings 63 and 62 respectively so that such rings, which are preferablymade of metal or at any rate have conducting surfaces,

may constitute electrical connections between contacts 84 and 85 on theone hand or between contacts 86 and 81 on the other hand when the ringsshift longitudinally of the axis of the Wheel I. Such shifting of therings 62 and 63 occurs whenever said rings rotate relatively in onedirection or the other about the hub of the wheel I, by reason of therollers 61 travelling in the grooves 66. A closure member 88 or flangemay be used to seal the opening between the hub 3 of the wheel and thehousing I4. Suitable electrical conductors will, of course, be connectedto the contacts 84, 85,86 and 81, corresponding to the conductors usedin the form hereinabove described and illustrated in Figs. l to 4.

A third modification, which is illustrated in Figs. 8 and 9, also has atubular extension 89 formed on or attached to the hub 3 of the wheel I,and surrounding the housing I4, with a flange or closure member 90secured thereto in any suitable way, for instance by means of the capscrews 9|. The member 90 in this form has a flat flange 92, and acylindrical flange 93 formed integral therewith. A suitable ring 94, ofL- shaped cross section, cooperates with the flanges 92 and 93 to forman entirely closed housing.

The-member 94 may be secured to the flange 92 by cap screws 95 or in anyother suitable manner, so as to form a substantially tight enclosure andprevent the entrance of dirt or water. The flange 93 has a cylindricalouter surface 96 having therein grooves 91 which preferably are shapedin the same way as the groove I3 shown in Fig. 3, that is, each groovehas two arms extending at an angle and in opposite directions from acentral point. A corresponding roller 98 cooperates with each groove 91in exactly the same manner that the roller I6 of Fig. 3 cooperates withits groove I3. It will be understood that three such rollers and groovesare preferably employed, as in the other forms.

Each roller 96 is supported on a pin or shaft 99 which may be the shankof a bolt, as shown best in Fig. 9, said bolt passing through the tworings |00 and I 0| and being secured by a suitable nut or the like |02.The two rings |00 and |0| are substantially parallel to one another andare spaced apart a suitable distance to allow the rollers 98 to rotatefreely yet without lost motion or end play, just as in the otherpreviously described forms. For this purpose the bolts themselves mayact as spacers in the well known manner, for example by providingtubular sleeves such as |03 thereon surrounding the bolts and ofsufficient length to hold'the rings |00 and |0| properly spaced when thenuts |02 are tightened.

A lug |04 suitably secured to the rings serves as an anchorage for thetwo springs |05 and |06. In this case, however, the springs areindicated as compression springs instead of tension springs and,therefore, the projecting ends of a small pin or the like |01 extendingthrough the lug |04 may serve to hold the ends of the said two springsin proper position. The remaining or outer ends of thel springs maybe.adjusted by means of screws |08 and |09, threaded through lugs |I0and III, respectively, formed in or on the casing member 94. By turningthe screws |08 and |09 it is possible to adjust the degree ofcompression of each of the said springs to the desired extent, gc; as tocenter the rollers 98 in their grooves A pair of contacts mounted in aholder or support |I2 is secured to the flange 92, the respectivecontacts ||3 and |I4 being suitably insulated, from the flange 92 andfrom one another. These contactmembers extend into proximity to theouter face of the ring |00, so that under certain conditions the ring|00 may abut. against said contacts and thereby provide electricalconnection between them. The remaining or outer ends of the contacts II3and |I4 extend outward into proximity to the two .contact rings |I5 and||6 respectively, which have suitable binding posts or other connectorsII1 and I|8 thereon for the attachment of conductors leading to theelectrical devices which are to be actuated. It will be understood thatthe contact rings or slip rings II5 and IIS are stationary and inpractice they will be secured to any suitable relatively stationaryportion of the vehicle, which will hold. them in proper proximity to thecontacts I|3 and 'II4. The contacts II3 and ||4 are slidably supportedin the holder ||2 and normally yieldably biased in any suitable mannerto remain out of contact with the ring |00, as well as with rings I|5and IIS. This may be accomplished by suitable springs or the like.

` Referring now to the diagram of electrical connections shown in Fig.l0, here Il! and |20 diagrammatically represent a connected pair ofinertia rings, such as those disclosed in each of the forms of theinvention hereinabove described, and it is assumed that these ringsjointly will move in an upward direction when acceleration exists. Uponso moving, the ring |20 will establiah electrical connection between theadjacently dispod electrical contacts |2I and |22, the effect of whichwill be to establish an electrical circuit through the conductor |22,the energizing winding |24`of a relay, the conductor |25, the source ofelectrical energy |20, the contact |22 and the ring |20.

The relay also has a further energizing winding |21, one end of which isconnected to the source of energy -|22 through the conductor |22 and theother end of which terminates in the contact |22. A contact element |20,carried by the armature |22 of the relay, will establish electricalconnection between the contacts |20 and |2| whenever current iiowsthrough the coil |24. so as to attract the amature |22. From the contactI2I current will then flow through the conductor |22 to the contact |24,the switch blade |22, the contact |22, the brake coil |21, conductor|22, the bi-metallic thermostat element |20 and conductor |40, and thusback to the source of energy |20. A block of insulating material I4| isinterposed between the switch blade |25 and the thermostat element |20,so as to prevent a short-circuit between said two devices.

The thermostatic switch is normally closed, that is, when there is nocurrent ilowing through the thermostatic member |20 the switch blade |20will establish and maintain c'onnection between the contacts lu and m.when the thermostatic element |20 becomes heated to a sui'ilcient extentit will ilex and thereby lift the resii- A The operation of the variousembodiments of f the invention hereinabove described is as follows:

Referring iirst to the form shown in Figs. 1, 2,`

3, and 4 it will be clear that whenever the wheel rotates the rings I2and I2 will be carried along in auch rotation, because they areconnected to the hub of said wheel through the springs 26 and 21.However these springs allow transient deviations between the rotation ofthe rings and of the wheel, because of their yieldability. Thus when anyexcessive acceleration occurs, the wheel and the rings will becomeshifted angularly about their Joint axis with respect to one another.and will remain so during such time as the acceleration is sufficient toovercome the forces exerted by the springs. Thus, should the rotation ofthe wheel I be suddenly slowed down by reason of excessive braking, orshould the wheel slip on the rails or on the road surface, it is obviousthat the inertia of the rings I2 and I0 will suflice to overcome thesprings, whereby the rings will move angularly about the axis of thewheel and in so doing the rollers I2 will move along the grooves l2,

Inaiunuch as these grooves are arranged at an angle, this shifting ofthe rollers along the grooves will produce an axial shift ol the pairoi' rings i2 and I2; in the direction to the right in Fig. l, or upwardin Fig. 3. This sluiting of the rings will cause the ring I2 to engagethe head 41 on the spring 42,'which will force the contact 42 intoengagement with the cooperating contact 42, thus establishing anelectrical connection between the conductors 42 and B4. It is clear thatthe same eilectwill be produced regardless of the direction of rotationof the wheel I, since in either case the rollers I5 will ride in onedirection or the other along the grooves i2, starting from the centralor neutral position indicated in Fig. 3, and because both arms of eachgroove are angularly inclined, it is immaterial ln which angulardirection the force produced by the acceleration acts, because in eitherevent the rings I0 and I0 will ride toward the head 41.

Itis also clear that this engagement of the ring I0 against the head 41will last only while the acceleration is sumcient to overcome thecombined action of the springs 22 and 21 to a sumcient degree4 to movethe rings I2 and i0 toward the said contact members. A great advantageresults from this, for there is no wear on the head 41 in the normalcondition of the parts, since the head engages the ring I0 only whenabnormal acceleration exists, that is, during the time that an actualelectrical signal or current is to be established through the conductors42 and 54 for the purpose of influencing the braking action, or give asignal or accomplish any other desired function. Mere normal iolting ofthe vehicle does not suilice to actuate the contacts,

and thus false signals are avoided.

The modication disclosed in Figs. 5, 6 and 7 will operate in a similarway, with the exception that since the grooves 02 in this modiilcatlonare continuous in one direction instead of extending at opposite anglesfrom a neutral or center point, as in the preceding form, the rings 22and 22 will travel in one axial direction when the acceleration is inone sense and will travel in the opposite axial direction when theacceleration is in the opposite sense. In other words, the rings,instead of always traveling away from the wheel, as in the ilrstdescribed form. will sometimes travel away from the wheel and at othertimes toward the wheel, so that for this reason a modification of thecontacts is necessary. y

Accordingly when the rings travel to the right in Fig. 6 the ring 62will establish electrical oonnection between the contacts 04 and 05,whereas when the rings travel in the other direction the ring 02 willestablish electrical connection between the contacts 02 and 21.

When insuillcient acceleration exists to overcome the forces exerted bythe springs 12 and 10, the rings will assume their normal or centralpositions, as illustrated in Figs. 6 and 7, wherein neither ring touchesany of the contacts. Hence in this form there is likewise no wear on thecontacts except when an electrical current is desired to ilow, as whencontrolling the brake mechanism or indicating the braking action, and nofalse electrical impulses are given by mere accidental Jolting and thelike of the vehicle.

In the third modification, disclosed in Figs. 8 and 9, the same kinds ofgrooves are employed as those shown in Fig. 3, hence the accelerationwill always produce motion oi the rings |00 and |0| toward the left fromthe positicn shown in Fig. 9, regardless of the sense the flexibleswitch member |35 away from one of the acceleration or the direction ofrotation of the wheel. The first effect of this shifting of the ringswill be that the ring ||||I will abut against the sliding contacts ||3and ||4, whereupon further shifting of the rings will cause saidcontacts to move to the left until they bear respectively against theslip rings Il! and ||8 whereby they establish electrical connectionbetween the conductors' attached to the binding posts ||1 and H3, whichcontrol the electrical currents.

Here again the ends of the sliding contact members ||3 and ||4 willnot'wear out easily since they bear against the slip rings only whenactually establishing the electrical connection so that there is noneedless wear on either the contacts or the slip rings when suchelectrical connection is not established. The chief difference betweenthis form of device and the iirst two is that in this form theprotecting case which encloses the inertia rings revolves with the wheelhub instead of being stationary with respect to the vehicle, as in thefirst two forms. An incidental advantage of this type is that thesprings |05 land |06 may be adjusted'readily by turning the screws |08and |09 without opening the protective casing.

The operation of the electrical circuits disclosed diagrammatically inFig. 10 may be readily understood from the diagram, but for the sake ofcompleteness it is briefly recapitulated here as follows:

When electrical connection is established between the contacts |2| and|22 which, it will be understood, represent any of the contacts shown inFigs. 1 to 9, by reason of upward motion of the rings ||9 and |20 whichlikewise represent any of the joined inertia rings of Figs. l to 9, theiirst effect will be to cause a flow of current from the source |26through the winding |24 of the relay, which thereupon will attract thearmature |33 downward about its pivot |43, whereby the contact member|33, which is also connected to the movable member of the relay, willestablish electrical connection between the contacts |29 and |3|, thusestablishing an electric current through winding |21 which is alsosupplied from the source |26.

This winding |21 is amply capable of holding down the armature |33without any aid from the winding |24, so that any momentary connectionbetween contacts |2| and |22, of suilicient duration merely to energizethe winding |24 for an interval long enough to bring down the armature|33, will establish a continuous flow of current through the winding|21, which will th'en continue to hold down the armature |33 even afterthe circuit again is broken at contacts |2| and |22. 'I'his will thenestablish and maintain a flow of current through the winding |31, whichis in series with the winding |21 and is supplied from the same source|26.'

The flow of current through the winding |31 must be maintained for atime interval suiiicient to actuate the valve |42, but obviously it isnot desired that current should continue to flow indefinitely throughthe coil |31. Therefore, the thermostatic element |39 is provided alsoin series with the coils |21 and |31, so that as soon as current flowsthrough this circuit the'thermostatic device |33 will begin to becomeheated thereby. When its temperature has risen sufficiently, it willbreak the circuit at contact points |34 and |36 by flexing and thuslifting or both of said contacts.

The resiliency or yieldability of the switch member will preventinstantaneous opening of the circuit, because it is necessary for thethermostatic member |33 to lift the switch member |35 through a slightdistance before the same will :dually leave the cooperating contacts |34and/or |36, thus giving suiilcient time for the relay coil |31 to act onthe valve |42. The

Y the thermostat |33l and if such thermostat is sluggish enough even a`rigid switch member may be found satisfactory. Y

When the circuit is broken, current will cease to iiow through thewindings |21 and |31 and the armature |33 will thereupon be raised bythe spring |44 so as to break the circuit also at the contacts |23 and|3|. Thereupon the thermostat |33 will cool spontaneously andreestablish the connections at |34 and |36 so that the circuit is againrestored to its initial condition ready to respond to the nextelectrical impulse conveyed through contacts |31 and |32, when next therings IIB and 233 are shifted, due to wheel slide or the like.

Particular attention is directed to the fact that in all the formsdisclosed the springs act so as to control the angular orcircumferential shift of the rings about the-wheel axis and that thesaid angular motion of the rings is converted into an axial shift bymeans of the rollers and grooves. Owing to the relatively small angle ofinclination of the grooves in which the rollers run, it is clear thatthis construction constitutes a self-locking device wherein lateralshocks, no matter how severe, cannot cause actuation of the rings andthat, nevertheless, said rings are verysensitive to the accelerationvariations desired to be indicated.

This self-locking effect will occur whenever the slope is so small thatthe trigonometric tangent of the angle made by the direction of thegroove with respect to the plane of rotation of the wheel is less thanthe coefficient of friction of the rollers in the groove or grooves.Under these conditions it is impossible for any axial force applied tothe rings to produce a sufliciently great component along the grooves toovercome the friction and cause motion along such grooves andthereforeunder such values of the groove angle as fuliil the said tangentcondition no lateral jolting can cause the rings to move axially. lThisis a distinct advantage over other forms of devices wherein springs actaxially or laterally to oppose the rings, which are free to move axiallyagainst such springs. whereupon a sudden side sway or lateral jolt ofthe vehicle will have the same effect as would a sudden acceleration,that is, a false signal will be given.

It will also be noted that the present device is located directly on thewheel or axle, that is, it is driven directly by such wheel or axle andnot by means of belts or other power transmitting devices. This givesadded simplicity and ruggedness to the present apparatus, which is ofcourse a highly important advantage in devices which are to be used withheavy vehicles such as railway cars, trucks, etc.

It will be understood that while electrical actuation has been disclosedin the present speciication, mechanical or pneumatic actuation couldlikewise be substituted if preferred for any reason. In other words, therings which move A axially are suitable for controlling any desiredmechanism whether it is an electrical contact device. an air valve. or arod or lever, such equivalentsbeingwellknownintheartsothatitisVbelievedtobeunnecessarytomorethanmention the fact that other means maybe employed of the electrical devices if preferred.

It should also be borne inmind that whileorthepartswillbesoproportionedand ustedthatanindicationorsignalwillbegiven when wheel slide is about to occur or actuallyoccurs, that is, when the brakes are applied too powerfully, it is ofcourse possible to adjust the elements in such way that an indication isgiven when anyvpredetermined arbitrary value of acceleration isexceeded, so that the device is not limited to actuation solely upon theactual occurrence of wheel slide but is designed to prevent wheel slide.For example in Fig. 8, the delicacy of response may be adjusted readilyby varying the settings of the springs I and I, and means for adjustingthe tensions of the springs used in the other modifications may ofcourse also be provided if desired.

Having described several modifications of the invention by illustrativeexamples thereof, it will, of course, be understood that thesemodifications are to be considered merely as illustrations and not aslimitations of the invention and that many moditlcations may be madewithout departing from the inventive principles involved.

For an understanding of the substance and scope of the inventionattention is directed to the following.

What we claim is:

1. An acceleration responsive device comprising a rotary member, aninertia member coaxial therewith, resilient means constraining saidmembers to rotate together under normal conditions but yieldable underthe stored energy in said inertia member to permit limited relativerotation between said members upon acceleration of said rotary memberbeyond the normal, the inertia member being guided in its relativerotation by inter-engaging guiding and radial supporting means,respectively, on said members, said supporting and guiding meanscomprising a plurality of circumferentially spaced rollers on one memberand trackways on the other member, one for each roller and in which therespective roller is guided on the other member, said trackways beingslightly inclined to a plane nomal to the axis of said members, wherebyacceleration of the rotary member beyond the normal causes the inertiamember to rotate relative thereto and in said rotation to shift axiallyto initiate a control impulse.

2. An acceleration responsive device according to claim 1 in which therollers normally occupy a position centrally of their respectivetrackways, whereby acceleration, positive or negative, of the rotarymember beyond the normal causes the inertia member to shift axially.-

3. An acceleration responsive device according to claim l in which saidtrackways incline in opposite directions from a central portion, wherebyupon sudden acceleration of the rotary member, positive or negative, theinertia member moves axially in the same direction.

4. An acceleration responsive device accordingvtoclaimiinwhichtheaxisoftherolllersis substantially normal to thedirection of the 5. An acceleration responsive device accordingvtoclaixnlinwhich theinertiamembercomprises said rings, said springsacting in opposite directions and each secured at one end to one, and atthe other end to the other, of said members.

7. An acceleration responsive device according to claim 1 in which thetrackways comprise grooves on one member cooperating with rollersextending into said grooves on the other member.

8. An acceleration responsive device comprising a rotary member, aninertia member coaxial therewith, resilient means constraining saidmembers to rotate together under normal conditions but yieldable understored energy in said inertia member to permit limited relative rotationbetween said members upon acceleration of said rotary member beyond thenormal, the inertia member being guided in its relative rotation byguide means on one of said members and means engaging said guide meanson the other of said members, the guide means being slightly inclined toa plane normal to the axis of said members, whereby the acceleration ofthe rotary member beyond the normal causes the inertia member to rotaterelative thereto and in said rotation to shift axially to provide acontrol force, the inertia member being mounted in a closed housing,between which and said inertia member the inter-engaging guide means arearranged, said housing and inertia member being a unitary structureassembled as a unit with the rotary member.

9. An acceleration responsive device comprising a rotary member, aninertia member coaxial therewith, generally tangentially-arrangedresilient means forming the sole means for constraining said members torotate together under normal conditions but yieldable under storedenergy in said inertia member to permit limited relative rotationbetween said members upon ac celeration of said rotary member beyond thenormal, the inertia member being guided in its relative rotation byguide means on one of said members and means engaging said guide meanson the other of said members, the guide means being slightly inclined toa plane normal to the axis of said members, whereby the acceleration ofthe rotary member beyond the normal causes the inertia member to rotaterelative thereto and in said rotation to shift axially to provide acontrol force, the rotary member being enclosed in a housing and theresilient means being connected with the housing through adjustablemeans extending outside the periphery of the housing and operable fromthe outside of the housing for adjusting the tension of said resilientmeans.

CAROLUS L. EKSERGIAN. JOSEPH H. COCMBES

